SERVER-49108 Convert buildInfo command to async implementation

1 files changed, 6 insertions, 20 deletions

diff --git a/src/mongo/transport/service_state_machine.cpp b/src/mongo/transport/service_state_machine.cpp
index ef278c1ba88..103dcf3fdcf 100644
--- a/src/mongo/transport/service_state_machine.cpp
+++ b/src/mongo/transport/service_state_machine.cpp
@@ -304,10 +304,6 @@ private:
     boost::optional<MessageCompressorId> _compressorId;
     Message _inMessage;
     Message _outMessage;
-
-    // Allows delegating destruction of opCtx to another function to potentially remove its cost
-    // from the critical path. This is currently only used in `processMessage()`.
-    ServiceContext::UniqueOperationContext _killedOpCtx;
 };
 
 Future<void> ServiceStateMachine::Impl::sourceMessage() {
@@ -456,13 +452,14 @@ Future<void> ServiceStateMachine::Impl::processMessage() {
         .then([this, &compressorMgr = compressorMgr, opCtx = std::move(opCtx)](
                   DbResponse dbresponse) mutable -> void {
             // opCtx must be killed and delisted here so that the operation cannot show up in
-            // currentOp results after the response reaches the client. The destruction is postponed
-            // for later to mitigate its performance impact on the critical path of execution.
+            // currentOp results after the response reaches the client. Destruction of the already
+            // killed opCtx is postponed for later (i.e., after completion of the future-chain) to
+            // mitigate its performance impact on the critical path of execution.
+            // Note that destroying futures after execution, rather that postponing the destruction
+            // until completion of the future-chain, would expose the cost of destroying opCtx to
+            // the critical path and result in serious performance implications.
             _serviceContext->killAndDelistOperation(opCtx.get(),
                                                     ErrorCodes::OperationIsKilledAndDelisted);
-            invariant(!_killedOpCtx);
-            _killedOpCtx = std::move(opCtx);
-
             // Format our response, if we have one
             Message& toSink = dbresponse.response;
             if (!toSink.empty()) {
@@ -551,11 +548,6 @@ void ServiceStateMachine::Impl::runOnce() {
             return sinkMessage();
         })
         .getAsync([this](Status status) {
-            // Destroy the opCtx (already killed) here, to potentially use the delay between
-            // clients' requests to hide the destruction cost.
-            if (MONGO_likely(_killedOpCtx)) {
-                _killedOpCtx.reset();
-            }
             if (!status.isOK()) {
                 _state.store(State::EndSession);
                 // The service executor failed to schedule the task. This could for example be that
@@ -659,12 +651,6 @@ void ServiceStateMachine::Impl::setCleanupHook(std::function<void()> hook) {
 void ServiceStateMachine::Impl::cleanupSession(const Status& status) {
     LOGV2_INFO(5127900, "Ending session", "error"_attr = status);
 
-    // Ensure the delayed destruction of opCtx always happens before doing the cleanup.
-    if (MONGO_likely(_killedOpCtx)) {
-        _killedOpCtx.reset();
-    }
-    invariant(!_killedOpCtx);
-
     cleanupExhaustResources();
 
     {